Profiteur is a visualiser for GHC .prof files.
cabal install profiteur
Installation via nix
nix-shell -p haskellPackages.profiteur
ghc --make -auto-all -prof your-program.hs
./your-program +RTS -p -RTS
profiteur your-program.prof
Open the output, your-program.prof.html, in a web browser.
See also example/Makefile.
A tree browser and a tree map are available to browse the profile.
Expand cost centres by clicking the chevrons in the tree browser or double-clicking them in the tree map.